Display screen or portion thereof with a graphical user interface



The sole FIGURE is a front view of a display screen or portion thereof with a graphical user interface showing our new design.

Outermost broken lines in the FIGURE show a display screen or portion thereof, and form no part of the claimed design. Broken lines in the FIGURE show portions of a graphical user interface that form no part of the claimed design.

Various elements of a depicted design are not limited to the placement on a display screen or portion thereof as shown in the FIGURE. 

CLAIM The ornamental design for a display screen or portion thereof with graphical user interface, as shown and described. 